The Anatomy of Light & Shadow



Observation is one of the most important skills used in creating representational drawings however if we want to portray a realistic three-dimensional object on a two-dimensional surface we have to create an illusion that the viewer believes to be three dimensional. This is where it helps to have a bit of academic knowledge and a basic understanding of how light and shadow work together.

Light & shadow also create a mood.

When LIGHT falls onto an object from a single source, it allows us to see it as a three-dimensional (3D) object. The quality of light affects how we see tones. A single light source will simplify the light and shadow whereas multiple sources or ambient light break down the solidity of the form.

Single Light Source
Note for beginners: Unfortunately, in most environments or everyday lighting situations, objects tend to show a minimal set of values which can be frustrating for beginners to translate.  Adding a lamp or shining a spotlight (called a single light source) on the subject will create a wider range of values making it easier to observe light on the form.

The areas where the light may not reach, or the object itself blocks the light creates shadows. There are two different kinds of shadows, a FORM SHADOW, and a CAST SHADOW. The form shadow is created where the object turns away from the light source, and the cast shadow is created by the object blocking the light source.

Tone

TONE is not a pure color. In painting, it is made by adding gray to a color.  It is created by the effects of light moving over a surface. The grayness or TONE of an object allows us to visually make sense of what we looking at on a two-dimensional (2D) surface. TONES are distinguished by tints or shades. A TINT is created from a tone + white or the white of the paper. A SHADE is created from a tone + black or a darkened pencil mark.


Simplify

When working with tones always work from general to specific, there may be a lot of tones to observe or tonal gradations to distinguish. In a single light source drawing, after the contour has been completed and proportions measured, the major shadow areas may be grouped together quickly blocked in and more detail may be added later on. Simplify light and dark areas by squinting your eyes.

Squint

This allows a smaller amount of light to flow into your vision, reducing the amount of color that you see and will help you see incremental tones as one large shape or as a whole.  Notice that when light hits the sphere (shown above right), more than half of the shape is lit. This area is referred to as “THE LIGHT SHAPE.”  The rest of the object is in shadow including the shadow created from the object, which is referred as “THE SHADOW SHAPE.”  Shadow shapes can be mapped out and measured just the same as contours.

Value

VALUE is the RELATIONSHIP of TONES on the surface of an object. Subtle variations or increments in tone create a gradation of gray tones or (neutrals) because light area becomes grayer or shaded as the object’s surface turns away from the light. The gradation of tones (more severe or less severe) help us determine the quality of light i.e. is it intense, diffused or ambient. The effect of strong direct lighting with shadows has a very different effect than diffused lighting with diffused shadows. The higher the contrast, the less scattered or more powerful the light source reads to the viewer and should be consistent throughout, i.e. if one object has a shadow, another object should have a shadow as well.

Depending on the quality of the light we can establish a relationship of the tones within a VALUE SCALE. This scale is a range of multiple TONES from dark to light that all relate to each other with lighter tones at one end and the darker tones at the other. The amount increments are what determine the tempo of the scale, i.e. how dramatic are the steps in tones from light to dark. You can make a VALUE SCALE using incremental tones to measure the lightness or darkness of a tone within a drawing. Remember as long as the steps in tones or tonal relationships are maintained, an object drawn on a 2D surface will appear 3D.

Single Light Source Value Scale in Six Steps

A complex VALUE SCALE may contain as many as 11 distinct values. However, any value scale can be simplified into fewer tones. The value scale shown below has been simplified into six tones.  Basic light and dark regions can be further broken down as you slowly “BRING UP” the drawing, which means that you gradually add more subtle shifts in the tones by slowly darkening areas. This changes the tonal relationships, so the secret to building complex TONAL RELATIONSHIPS is to build them slowly.

Within the Light and Shadow Shapes

#1. The HIGHLIGHT is the lightest area of the sphere and is also known as “THE LIGHTEST LIGHT.”  The shinier the object, the brighter the highlight will be compared to the rest of your values scale.

#2.  The MID TONE or the AVERAGE TONE is the highlight and the halftone #3.  The tricky part is to render the average tone so that it accents the form of the object; this is the essence of the 3D shape of the object and is responsible for creating the basic form.

#1 - Highlight, #2 -Average Tone, #3 - Half Tone, 
  #4 - Core Shadow, #5 - Reflective Light, #6 - Cast Shadow  
#3.  The HALF TONE or “LOCAL COLOR” is the darkest value within the light shape.  This is where the light itself fades into the shadow shape of the object.  This is where the object “turns” away from the light.

#4.  The CORE SHADOW is the area where light cannot reach the surface of the object. This is the hardest part of the value system for new students to grasp.

#5.  REFLECTIVE LIGHT is created from the light that bounces off of the table or reflects from the surface upon which the object rests. It is always lighter than the core shadow but, darker than the entire light shape.  It usually complements the core shadow and rounds off the form of the object.  Note: Be careful to not make it too bright.  Think of it as the moon compared with the sun. The FORM SHADOW is created from the combination of the CORE SHADOW and the REFLECTED LIGHT. They complete the form of the object, so this is why they are referred to as the form shadow.

#6.  The CAST SHADOW is the shadow which is “cast” behind or falls underneath the object.  Cast Shadows have three major characteristics.  1) They are always darker than the form shadow.  2) All shadows have soft edges but, cast shadows have harder edges the form shadow.  3) Cast shadows are darker in the area that is closest to the object that is creating the shadow.

The cast shadow also has changed in tone, but that will be covered in a later article.

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